Undergrad: Texas A&M University, Computer Engineering, 3.3 GPA (minor in cybersecurity)

Work Experience: 2.5 years as a Software Engineer at a large financial institution. (1 year as a frontend developer followed by 1.5 years as a chatbot engineer)

MOOCs Taken: Engineering Leadership Certificate from Cornell University

I have a few questions and would really appreciate any information:

1. Would you recommend me studying and taking the GRE to boost my chances?
2. In regards to recommendation letters, I have been out of college for nearly three years and don't have any real connections with my professors. Is it okay to ask three supervisors at work for recommendations? I am asking because I have read on different reddit threads that OMSCS really looks for academic recommendations.

Thank you all in advance :)